Interests of Both Borrowers and Lenders Must Be Taken Into Account

BUDAPEST—Hungary's top court Monday ruled that lawmakers can adopt legislation allowing retroactive changes to foreign-currency loan contracts, but the changes must take into account the interests of both borrowers and the lenders.

Foreign-currency loans—mainly mortgages tied to the Swiss franc—were hugely popular before the financial crisis because they were much cheaper to service than local-currency loans. They have become a major...